Lubricant composition

ABSTRACT

Disclosed herein is a process for lubricating an internal combustion engine with a lubricant composition that may be substantially ash free. The ashless lubricant composition described herein may comprise primary antioxidants, such as aminic diphenyl amines, alkylated phenyl-naphthyl amines, and phenolic antioxidants. The ashless lubricant composition described herein may also comprise sulfur containing products that may work as secondary antioxidants. Other components such as ashless antiwear components, dispersants, pour point depressants, friction modifiers, and metal deactivators may also be used to formulate an ashless lubricant composition according to an embodiment.

FIELD OF THE INVENTION

This disclosure relates to formulated ashless lubricant compositions, methods for using said ashless lubricant compositions in internal combustion engines, and to internal combustion engine systems operating with the lubricant compositions described herein.

BACKGROUND OF THE INVENTION

Engine oils are utilized to lubricate internal combustion engines, but the ash that they contain can damage a car's catalytic converter. To prevent this, cars use a simple trap to isolate any particles from the exhaust and contain the ash that they contain. Ash has also been found to initiate a destructive condition in Gasoline Direct Injected engines that is called Low Speed Pre-Ignition (LSPI).

OBJECTS AND SUMMARY OF THE INVENTION

In certain embodiments, disclosed is a process for lubricating an internal combustion engine. The process may comprise adding a lubricant composition to an internal combustion engine. The lubricant composition may comprise a base oil, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amine antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives. The lubricant composition may be ashless.

In certain embodiments, disclosed is a process comprising running an internal combustion engine with a lubricant composition. The lubricant composition may be ashless and may comprise a base oil, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amine antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives.

In certain embodiments, disclosed is a system comprising an internal combustion engine and an ashless lubricant composition. The ashless lubricant composition may comprise a base oil, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amine antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives.

DETAILED DESCRIPTION

Engine oils are utilized to lubricate internal combustion engines, but the ash that they contain can damage a car's catalytic converter. Ash has also been found to initiate a destructive condition in Gasoline Direct Injected engines that is called Low Speed Pre-Ignition (LSPI). Accordingly, disclosed herein are ashless lubricant compositions that may be utilized to lubricate internal combustion engines. In certain embodiments, a suitable lubricant composition is an ashless internal combustion engine lubricant. Suitable ashless lubricant compositions may comprise, among other optional components, a base oil as well as primary and secondary antioxidants.

The term “ashless” as used herein may indicate that the lubricant composition comprises less than about 0.5 wt %, less than about 0.4 wt %, less than about 0.3 wt %, less than about 0.2 wt %, less than about 0.1 wt %, less than about 0.05 wt %, less than about 0.01 wt %, less than about 0.001 wt %, less than about 0.0001 wt %, or no (i.e. 0 wt %) overbased calcium, magnesium, salts of alkyl aromatic sulfonates, phenates, or salicylates, calculated for each component independently or in total, based on the total weight of the lubricant composition.

The base oil, or lubricating base oil or base stock, may be the largest component by weight of a finished fully formulated lubricating composition.

Lubricating base oils that may be useful in the present disclosure are both natural oils and synthetic oils as well as non-conventional oils (or mixtures thereof) which can be used unrefined, refined, or re-refined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one lubricating oil property. One skilled in the art is familiar with many purification processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration and percolation. Re-refined oils are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

Groups I, II, III, IV and V are broad base oil stock categories developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for lubricant base oils. Group I base stocks have a viscosity index of from 80 to 120 and contain greater than 0.03% sulfur and/or less than 90% saturates. Group II base stocks have a viscosity index of from 80 to 120, and contain less than or equal to 0.03% sulfur, and greater than or equal to 90% saturates. Group III base stocks have a viscosity index greater than 120 and contain less than or equal to 0.03% sulfur and greater than 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stocks includes base stocks not included in Groups I-IV. The table below summarizes properties of each of these five groups.

Saturates Sulfur Viscosity Index Group I <90 >0.03% ≥80 and <120 Group II ≥90 ≤0.03% ≥80 and <120 Group III ≥90 ≤0.03% ≥120 Group IV ---- polyalphaolefins (PAO) ---- Group V ---- all other base stocks not of Groups I-IV ----

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. In a certain embodiment, natural oils include mineral oils. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks, including synthetic oils such as polyalphaolefins, alkyl aromatics and synthetic esters are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C₆, C₈, C₁₀, C₁₂, C₁₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from 250 to 3,000, although PAO's may be made in viscosities up to 100 cSt (100° C.). The PAOs may typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include, but are not limited to, C2 to C32 alphaolefins, for example C8 to C16 alphaolefins, such as 1-hexene, 1-octene, 1-decene, 1-dodecene and the like. Polyalphaolefins may include poly-1-hexene, poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of C14 to C18 may be used to provide low viscosity base stocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs may be predominantly trimers and tetramers of the starting olefins, with minor amounts of the higher oligomers, having a viscosity range of 1.5 to 12 cSt. PAO fluids of particular use may include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof. Bi-modal mixtures of PAO fluids having a viscosity range of 1.5 to about 100 cSt or to about 300 cSt may be used if desired.

The PAO fluids may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example the methods disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C14 to C18 olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant composition base oils include wax isomerate base stocks and base oils, comprising hydroisomerized waxy stocks (e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker bottoms, etc.), hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocks and base oils, and other wax isomerate hydroisomerized base stocks and base oils, or mixtures thereof. Fischer-Tropsch waxes, the high boiling point residues of Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with very low sulfur content. The hydroprocessing used for the production of such base stocks may use an amorphous hydrocracking/hydroisomerization catalyst, such as one of the specialized lube hydrocracking (LHDC) catalysts or a crystalline hydrocracking/hydroisomerization catalyst, for example a zeolitic catalyst. For example, one useful catalyst is ZSM-48 as described in U.S. Pat. No. 5,075,269. Processes for making hydrocracked/hydroisomerized distillates and hydrocracked/hydroisomerized waxes are described, for example, in U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Particularly favorable processes are described in European Patent Application Nos. 464546 and 464547, also incorporated herein by reference. Processes using Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172 and 4,943,672.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized (wax isomerate) base oils be advantageously used in the instant disclosure, and may have useful kinematic viscosities at 100° C. of 3 cSt or 3.5 cSt to 25 cSt, 30 cSt or 50 cSt, as exemplified by GTL 4 with kinematic viscosity of 4.0 cSt at 100° C. and a viscosity index of 141. These Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and other wax-derived hydroisomerized base oils may have useful pour points of −20° C. or lower, and under some conditions may have advantageous pour points of −25° C. or lower, with useful pour points of −30° C. to −40° C. or lower. Useful compositions of Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils, and wax-derived hydroisomerized base oils are recited for example in U.S. Pat. Nos. 6,080,301; 6,090,989 and 6,165,949.

Hydrocarbyl aromatics can be used as base oil or base oil component and can be any hydrocarbyl molecule that contains at least 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The aromatic can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can also be comprised of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl groups and other related hydrocarbyl groups. The hydrocarbyl groups can range from C6 up to C60, for example from C8 to C20. A mixture of hydrocarbyl groups may be advantageous, and up to three such substituents may be present.

The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at 100° C. for the hydrocarbyl aromatic component may be from about 3 cSt or about 3.4 cSt to about 20 cSt or about 50 cSt. In one embodiment, an alkyl naphthalene where the alkyl group is primarily comprised of 1-hexadecene is used. Other alkylates of aromatics can be advantageously used. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like. Useful concentrations of hydrocarbyl aromatic in a lubricant oil composition can be from about 2% or about 4% to about 15%, about 20% or about 25%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the present disclosure may be produced by well-known Friedel-Crafts alkylation of aromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York, 1963. For example, an aromatic compound, such as benzene or naphthalene, is alkylated by an olefin, alkyl halide or alcohol in the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many homogeneous or heterogeneous, solid catalysts are known to one skilled in the art. The choice of catalyst depends on the reactivity of the starting materials and product quality requirements. For example, strong acids such as AlCl3, BF3, or HF may be used. In some cases, milder catalysts include FeCl3 or SnCl4. Newer alkylation technology uses zeolites or solid super acids.

Esters may also comprise a useful base stock, for example esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di-(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters may be those which are obtained by reacting one or more polyhydric alcohols, for example hindered polyols (such as the neopentyl polyols, e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol) with alkanoic acids containing at least 4 carbon atoms, for instance C5 to C30 acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Suitable synthetic ester components include the esters of trimethylol propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or dipentaerythritol with one or more monocarboxylic acids containing from 5 to 10 carbon atoms. These esters are widely available commercially, for example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company. In a certain embodiment, a synthetic ester includes trimethylolpropane trinonoate.

Also useful are esters derived from renewable material such as coconut, palm, rapeseed, soy, sunflower and the like. These esters may be monoesters, di-esters, polyol esters, complex esters, or mixtures thereof. These esters are widely available commercially, for example, the Mobil P-51 ester of ExxonMobil Chemical Company.

In certain embodiments, diesters are suitable base stocks and may be formed by esterification of linear or branched C6-C15 aliphatic alcohols with one or more dibasic acids such as adipic, sebacic or azelaic acids. Examples of diesters are di-2-ethylhexyl sebacate and dioctyl adipate. A synthetic polyol ester base oil may be formed by esterification of an aliphatic polyol with carboxylic acid. An aliphatic polyol may contain from 4 to 15 carbon atoms and have from 2 to 8 hydroxyl groups. Examples of polyols include trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyl glycol, tripentaerythritol and mixtures thereof.

In certain embodiments, a carboxylic acid reactant used to produce a synthetic polyol ester base oil is selected from aliphatic monocarboxylic acid or a mixture of aliphatic monocarboxylic acid and aliphatic dicarboxylic acid. The carboxylic acid may contain from 4 to 12 carbon atoms and may be straight or branched chain aliphatic acids. Mixtures of monocarboxylic acids may be used. In one embodiment, a polyol ester base oil is prepared from technical pentaerythritol and a mixture of C4-C12 carboxylic acids. Technical pentaerythritol is a mixture that includes about 85 to about 92 wt % monopentaerythritol and about 8 to about 15 wt % dipentaerythritol. A typical commercial technical pentaerythritol contains about 88 wt % monopentaerythritol and about 12 wt % of dipentaerythritol.

Other useful fluids of lubricating viscosity include non-conventional or unconventional base stocks that have been processed, e.g. catalytically, or synthesized to provide high performance lubrication characteristics.

Non-conventional base stocks/base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks.

GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of lubricating viscosity that are generally derived from hydrocarbons; for example, waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials such as, for example, by distillation and subsequently subjected to a final wax processing step which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point; (2) synthesized wax isomerates, comprising, for example, hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); for example hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials, especially, hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxed wax or waxy feed, for example F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100° C. of from about 2 mm²/s to about 50 mm²/s (ASTM D445). They are further characterized typically as having pour points of about −5° C. to about −40° C. or lower (ASTM D97). They may also be characterized as having viscosity indices of 80 to 140 or greater (ASTM D2270).

The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived may advantageously be an F-T material (i.e., hydrocarbons, waxy hydrocarbons, wax).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) and hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorous and aromatics make this material especially suitable for the formulation of low sulfur, sulfated ash, and phosphorus (low SAP) products.

Base oils for use in the formulated lubricating oils useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group I, Group III, Group IV, and Group V oils and mixtures thereof, in some embodiments API Group II, Group III, Group IV, and Group V oils and mixtures thereof, in certain embodiments the Group III to Group V base oils due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated but should be kept to a minimum, i.e. amounts only associated with their use as diluent/carrier oil for additives used on an “as-received” basis. In regard to the Group II stocks, in some embodiments the Group II stock may be in the higher quality range associated with that stock, i.e. a Group II stock having a viscosity index in the range 100 cSt<VI<120 cSt.

The lubricating base oil or base stock constitutes the major component of the lubricant composition of the present disclosure. In an embodiment, a lubricating oil base stock for the inventive lubricant composition is from any of about 80 wt % (weight percent), about 81 wt %, about 82 wt %, about 83 wt %, about 84 wt %, about 85 wt %, about 86 wt %, about 87 wt % or about 88 wt % to any of about 89 wt %, about 90 wt %, about 91 wt %, about 92 wt %, about 93 wt %, about 94 wt %, about 95 wt %, about 96 wt %, about 97 wt %, about 98 wt %, about 99 wt %, about 99.1 wt %, about 99.2 wt %, about 99.3 wt %, about 99.4 wt %, about 99.5 wt %, about 99.6 wt % or about 99.7 wt %, based on the total weight of the fully formulated lubricant composition.

Group III base stocks may be GTL and Yubase Plus (hydroprocessed base stock). Group V base stocks may include alkylated naphthalene, synthetic esters and combinations thereof.

In some embodiments, the base oils or base stocks described above have a kinematic viscosity, according to ASTM standards, of about 2.5 cSt or about 4 cSt to any of about 6 cSt, about 8 cSt or about 9 cSt, about 12 cSt (or mm²/s) at 100° C. In other embodiments, base stocks may have a kinematic viscosity of up to about 100 cSt, about 150 cSt, about 200 cSt, about 250 cSt or about 300 cSt at 100° C.

In some embodiments, a base stock may comprise a random or block polyalkylene glycol copolymer comprising ethylene oxide and propylene oxide units. A copolymer may comprise from any of about 30 wt %, about 50 wt % or about 60 wt % to any of about 70 wt %, about 85 wt % or about 95 wt % ethylene oxide units with the remainder being propylene oxide units.

In certain embodiments, a base oil comprises those selected from the group consisting of API groups II III and IV. Included are GTL derived base oils. One or more base oils selected from groups II, III and IV may be combined with one or more esters as described above, for instance one or more diesters and/or triesters. In such mixtures, an ester may be present from any of about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %, about 4 wt %, about 5 wt %, about 6 wt %, about 7 wt % or about 8 wt % to any of about 9 wt %, about 10 wt %, about 11 wt %, about 12 wt %, about 13 wt %, about 14 wt % or about 15 wt %, based on a fully formulated lubricating oil.

In some embodiments, the lubricant composition may comprise a diester component having the following structure:

wherein R₁, R₂, R₃, and R₄ are independently a straight or branched chain C₂ to C₁₇ hydrocarbon group.

In some embodiments, R₁, R₂, R₃ and R₄ are selected such that the kinematic viscosity of the composition at a temperature of 100° C. is about 3 mm²/sec or greater. In some or other embodiments, R₁, R₂, R₃ and R₄ are selected such that the pour point of the resulting formulated oil is about −10° C. or lower, about −25° C. or lower or about −40° C. or lower. In some embodiments, R₁ and R₂ are selected to have a combined carbon number (i.e., total number of carbon atoms) of from 6 to 14. In these or other embodiments, R₃ and R₄ are selected to have a combined carbon number of from 10 to 34. Depending on the embodiment, such resulting diester species can have a molecular mass from about 340 atomic mass units (amu) to about 780 amu.

In some embodiments, a diester component is substantially homogeneous. In some or other embodiments, a diester component comprises a variety (i.e., a mixture) of diester species.

In some embodiments, the diester component comprises at least one diester species derived from a C₈ to C₁₆ olefin and a C₂ to C₁₈ carboxylic acid. A diester species may be prepared by reacting each —OH group (on the intermediate) with a different acid, but such diester species can also be made by reacting each —OH group with the same acid.

In some embodiments, a diester component in the lubricant composition comprises a diester species selected from the group consisting of decanoic acid 2-deanoyloxy-1-hexyl-octyl ester and its isomers, tetradecanoic acid-1-hexyl-2-tetradecanoyloxy-octyl esters and its isomers, dodecanoic acid 2-dodecanoylaxy-1-hexyl-octyl ester and its isomers, hexanoic acid 2-hexanoyloxy-1-hexy-octyl ester and its isomers, octanoic acid 2-octanoyloxy-1-hexyl-octyl ester and its isomers, hexanoic acid 2-hexanoyloxy-1-pentyl-heptyl ester and isomers, octanoic acid 2-octanoyloxy-1-pentyl-heptyl ester and isomers, decanoic acid 2-decanoyloxy-1-pentyl-heptyl ester and isomers, decanoic acid-2-cecanoyloxy-1-pentyl-heptyl ester and its isomers, dodecanoic acid-2-dodecanoyloxy-1-pentyl-heptyl ester and isomers, tetradecanoic acid 1-pentyl-2-tetradecanoyloxy-heptyl ester and isomers, tetradecanoic acid 1-butyl-2-tetradecanoyloxy-hexy ester and isomers, dodecanoic acid-1-butyl-2-dodecanoyloxy-hexyl ester and isomers, decanoic acid 1-butyl-2-decanoyloxy-hexyl ester and isomers, octanoic acid 1-butyl-2-octanoyloxy-hexyl ester and isomers, hexanoic acid 1-butyl-2-hexanoyloxy-hexyl ester and isomers, tetradecanoic acid 1-propyl-2-tetradecanoyloxy-pentyl ester and isomers, dodecanoic acid 2-dodecanoyloxy-1-propyl-pentyl ester and isomers, decanoic acid 2-decanoyloxy-1-propyl-pentyl ester and isomers, octanoic acid 1-2-octanoyloxy-1-propyl-pentyl ester and isomers, hexanoic acid 2-hexanoyloxy-1-propyl-pentyl ester and isomers and mixtures thereof.

Methods which can be employed in making diesters suitable for the lubricant composition described herein are further described for example in U.S. Patent Application Publications 2009/0159837 and 2009/0198075. More specifically, in some embodiments, processes for making diester species comprise: epoxidizing an olefin (or quantity of olefins) having a carbon number of from 8 to 16 to form an epoxide comprising an epoxide ring; opening the epoxide ring to form a diol; and esterifying (i.e., subjecting to esterification) the diol with an esterifying species to form a diester species, wherein such esterifying species are selected from the group consisting of carboxylic acids, acyl acids, acyl halides, acyl anhydrides and combinations thereof, wherein such esterifying species have a carbon number from 2 to 18; and wherein the diester species have a viscosity of about 3 mm²/sec or more at a temperature of 100° C.

Diester species may be prepared by epoxidizing an olefin having from about 8 to about 16 carbon atoms to form an epoxide comprising an epoxide ring. The epoxidized olefin is reacted directly with an esterifying species to form a diester species, wherein the esterifying species is selected from the group consisting of carboxylic acids, acyl halides, acyl anhydrides, and combinations thereof, wherein the esterifying species has a carbon number of from 2 to 18, and wherein the diester species has a viscosity and a pour point suitable for use as a finished oil.

In some embodiments, the olefin used is a reaction product of a Fischer-Tropsch process. In these or other embodiments, the carboxylic acid can be derived from alcohols generated by a Fischer-Tropsch process and/or it can be a bio-derived fatty acid.

In some embodiments, the olefin is an α-olefin (i.e., an olefin having a double bond at a chain terminus). In such embodiments, it is usually necessary to isomerize the olefin so as to internalize the double bond. Such isomerization is typically carried out catalytically using a catalyst such as, but not limited to, crystalline aluminosilicate and like materials and aluminophosphates. See, e.g., U.S. Pat. Nos. 2,537,283; 3,211,801; 3,270,085; 3,327,014; 3,304,343; 3,448,164; 4,593,146; 3,723,564 and 6,281,404.

Fischer-Tropsch alpha olefins (α-olefins) can be isomerized to the corresponding internal olefins followed by epoxidation. The epoxides can then be transformed to the corresponding diols via epoxide ring opening followed by di-acylation (i.e., di-esterification) with the appropriate carboxylic acids or their acylating derivatives. It is typically necessary to convert alpha olefins to internal olefins because diesters of alpha olefins, especially short chain alpha olefins, tend to be solids or waxes. “Internalizing” alpha olefins followed by transformation to the diester functionalities introduces branching along the chain which reduces the pour point of the intended products. The ester groups with their polar character would further enhance the viscosity of the final product. Adding ester branches will increase the carbon number and hence viscosity. It can also decrease the associated pour and cloud points. In some embodiments, there may be a few longer branches rather than many short branches, as increased branching tends to lower the viscosity index (VI).

Regarding the step of epoxidizing (i.e., the epoxidation step), in some embodiments, the above-described olefin (in one embodiment an internal olefin) can be reacted with a peroxide (e.g., H₂O₂) or a peroxy acid (e.g., peroxyacetic acid) to generate an epoxide. See, e.g., D. Swern, in Organic Peroxides Vol. II, Wiley-Interscience, New York, 1971, pp. 355-533; and B. Plesnicar, in Oxidation in Organic Chemistry, Part C, W. Trahanovsky (ed.), Academic Press, New York 1978, pp. 221-253. Olefins can be efficiently transformed to the corresponding diols by highly selective reagent such as osmium tetra-oxide (M. Schroder, Chem. Rev. vol. 80, p. 187, 1980) and potassium permanganate (Sheldon and Kochi, in Metal-Catalyzed Oxidation of Organic Compounds, pp. 162-171 and 294-296, Academic Press, New York, 1981).

Regarding the step of epoxide ring opening to the corresponding diol, this step can be acid-catalyzed or based-catalyzed hydrolysis. Exemplary acid catalysts include, but are not limited to, mineral-based Brönsted acids (e.g., HCl, H₂SO₄, H₃PO₄, perhalogenates, etc.), Lewis acids (e.g., TiCl₄ and AlCl₃) solid acids such as acidic aluminas and silicas or their mixtures, and the like. See, e.g., Chem. Rev. vol. 59, p. 737, 1959; and Angew. Chem. Int. Ed., vol. 31, p. 1179, 1992. Based-catalyzed hydrolysis typically involves the use of bases such as aqueous solutions of sodium or potassium hydroxide.

Regarding the step of esterifying (esterification), an acid is typically used to catalyze the reaction between the —OH groups of the diol and the carboxylic acid(s). Suitable acids include, but are not limited to, sulfuric acid (Munch-Peterson, Org. Synth., V, p. 762, 1973), sulfonic acid (Allen and Sprangler, Org. Synth., III, p. 203, 1955), hydrochloric acid (Eliel et al., Org. Synth., IV, p. 169, 1963), and phosphoric acid (among others). In some embodiments, the carboxylic acid used in this step is first converted to an acyl chloride (via, e.g., thionyl chloride or PCl3). Alternatively, an acyl chloride could be employed directly. Wherein an acyl chloride is used, an acid catalyst is not needed and a base such as pyridine, 4-dimethylaminopyridine (DMAP) or triethylamine (TEA) is typically added to react with an HCl produced. When pyridine or DMAP is used, it is believed that these amines also act as a catalyst by forming a more reactive acylating intermediate. See, e.g., Fersh et al., J. Am. Chem. Soc., vol. 92, pp. 5432-5442, 1970; and Hofle et al., Angew. Chem. Int. Ed. Engl., vol. 17, p. 569, 1978.

Regardless of the source of the olefin, in some embodiments, the carboxylic acid used in the above-described method is derived from biomass. In some such embodiments, this involves the extraction of some oil (e.g., triglyceride) component from the biomass and hydrolysis of the triglycerides of which the oil component is comprised so as to form free carboxylic acids.

In some embodiments, the lubricant composition may comprise a triester component having the following chemical structure:

Wherein R₁, R₂, R₃, and R₄ are independently selected from C₂ to C₂ hydrocarbon groups (hydrocarbon groups with from 2 to 20 carbon atoms), and wherein “n” is an integer from 2 to 20.

Selection of R₁, R₂, R₃ and R₄, and n can follow any or all of several criteria. For example, in some embodiments, R₁, R₂, R₃ and R₄ and n are selected such that the kinematic viscosity of the composition at a temperature of 100° C. is typically about 3 mm²/sec or greater. In some or other embodiments, R₁, R₂, R₃, and R₄ and n are selected such that the pour point of the resulting finished oil is about −10° C. or lower, e.g., about −25° C. or about −40° C. or lower. In some embodiments, R₁ is selected to have a total carbon number of from 6 to 12. In these or other embodiments, R₂ is selected to have a carbon number of from 1 to 20. In these or other embodiments, R₃ and R₄ are selected to have a combined carbon number of from 4 to 36. In these or other embodiments, n is selected to be an integer from 5 to 10. Depending on the embodiment, such resulting triester species can typically have a molecular mass from about 400 amu or about 450 amu to about 1000 amu or about 1100 amu.

In some embodiments, the ester component may be substantially homogeneous in terms of its triester component. In some other embodiments, the triester component comprises a variety (i.e., a mixture) of triester species. In these or other embodiments, such above-described triester components further comprise one or more triester species.

In some of the above-described embodiments, a triester component comprises one or more triester species of the type 9,10-bis-alkanoyloxy-oetadecanoic acid alkyl ester and isomers and mixtures thereof, where the alkyl is selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl; and where the alkanoyloxy is selected from the group consisting of ethanoyloxy, propanoyoxy, butanoyloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, octanoyloxy, nonaoyloxy, decanoyloxy, undacanoyloxy, dodecanoyloxy, tridecanoyloxy, tetradecanoyloxy, pentaclecanoyloxy, hexadeconoyloxy, and octadecanoyloxy, 9,10-bis-hexanoyloxy-octadecanoic acid hexyl ester and 9,10-bis-decanoyloxy-octadecanoic acid decyl ester are exemplary such triesters.

One method of preparing triester species is described in U.S. Pat. No. 7,544,645. In some embodiments, processes for making triester species comprises the steps: esterifying (i.e., subjecting to esterification) a mono-unsaturated fatty acid (or quantity of mono-unsaturated fatty acids) having a carbon number of from 10 to 22 with an alcohol to form an unsaturated ester (or a quantity thereof); epoxidizing the unsaturated ester to form an epoxy-ester species comprising an epoxide ring; opening the epoxide ring of the epoxy-ester species to form a dihydroxy-ester: and esterifying the dihydroxy-ester with an esterifying species to form a triester species, wherein such esterifying species are selected from the group consisting of carboxylic acids, acyl halides, acyl anhydrides, and combinations thereof, and wherein such esterifying species have a carbon number of from 2 to 19.

In another embodiment, the method can comprise reducing a monosaturated fatty acid to the corresponding unsaturated alcohol. The unsaturated alcohol is then epoxidized to an epoxy fatty alcohol. The ring of the epoxy fatty alcohol is opened to make the corresponding triol; and then the triol is esterified with an esterifying species to form a triester species, wherein the esterifying species is selected from the group consisting of carboxylic acids, acyl halides, acyl anhydrides and combinations thereof, and wherein the esterifying species has a carbon number of from 2 to 19. The structure of a triester prepared by the foregoing method would be as follows:

wherein R₂, R₃ and R₄ are independently selected from C₂ to C₂ hydrocarbon groups, for instance selected from C₄ to C₁₂ hydrocarbon groups.

In another embodiment, the method can comprise reducing a monosaturated fatty acid to the corresponding unsaturated alcohol; epoxidizing the unsaturated alcohol to an epoxy fatty alcohol; and esterifying the fatty alcohol epoxide with an esterifying species to form a triester species, wherein the esterifying species is selected from the group consisting of carboxylic acids, acyl halides, acyl anhydrides, and combinations thereof and wherein the esterifying species has a carbon number of from 2 to 19.

In some embodiments, where a quantity of triester species is formed, the quantity of triester species can be substantially homogeneous, or it can be a mixture of two or more different such triester species. Additionally or alternatively, in some embodiments, such methods further comprise a step of blending a triester composition(s) with one or more diester species.

In some embodiments, such methods produce compositions comprising at least one triester species of the type 9,10-bis-alkanoyloxy-octadecanoic acid alkyl ester and isomers and mixtures thereof where the alkyl is selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl and octadecyl; and where the alkanoyloxy is selected from the group consisting of ethanoyloxy, propanoyoxy, butanoyloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, octanoyloxy, nonaoyloxy, decanoyloxy, undacanoyloxy, dodecanoyloxy, tridecanoyloxy, tetradecanoyloxy, pentadecanoyloxy, hexadeconoyloxy, and octadecanoyloxy. Exemplary such triesters include, but not limited to, 9,10-bis-hexanoyloxy-octadecanoic acid hexyl ester; 9,10-bis-octanoyloxy-octadecanoic acid hexyl ester; 9,10-bis-decanoyloxy-octadecanoic acid hexyl ester; 9,10-bis-dodecanoyoxy-octadecanoic acid hexyl ester; 9,10-bis-hexanoyloxy-octadecanoic acid decyl ester; 9,10-bis-decanoyloxy-octadecanoic acid decyl ester; 9,10-bis-octanoyloxy-octadecanoic acid decyl ester; 9,10-bis-dodecanoyloxy-octadecanoic acid decyl ester; 9,10-bis-hexanoyloxy-octadecanoic acid octyl ester; 9,10-bis-octanoyloxy-octadecanoic acid octyl ester: 9,10-bis-decanoyloxy-octadecanoic acid octyl ester; 9,10-bis-dodecanoyloxy-octadecanoic acid octyl ester; 9,10-bis-hexanoyloxy-octadecanoic acid dodecyl ester; 9,10-bis-octanoyloxy-octadecanoic acid dodecyl ester; 9,10-bis-decanoyloxy-octadecanoic acid dodecyl ester; 9,10-bis-doclecanoyloxy-octadecanoic acid dodecyl ester; and mixtures thereof.

In some such above-described method embodiments, the mono-unsaturated fatty acid can be a bio-derived fatty acid. In some or other such above-described method embodiments, the alcohol(s) can be FT-produced alcohols.

In some method embodiments, the step of esterifying (i.e., esterification) the mono-unsaturated fatty acid can proceed via an acid-catalyzed reaction with an alcohol using, e.g., H2SO4 as a catalyst. In some or other embodiments, the esterifying can proceed through a conversion of the fatty acid(s) to an acyl halide (chloride, bromide, or iodide) or acyl anhydride, followed by reaction with an alcohol.

Regarding the step of epoxidizing (i.e., the epoxidation step), in some embodiments, the above-described mono-unsaturated ester can be reacted with a peroxide (e.g., H₂O₂) or a peroxy acid (e.g., peroxyacetic acid) to generate an epoxy-ester species. See, e.g., D. Swern, in Organic Peroxides Vol. II, Wiley-Interscience, New York, 1971, pp. 355-533; and B. Plesnicar, in Oxidation in Organic Chemistry, Part C, W. Trahanovsky (ed.), Academic Press, New York 1978, pp. 221-253. Additionally or alternatively, the olefinic portion of the mono-unsaturated ester can be efficiently transformed to the corresponding dihydroxy ester by highly selective reagents such as osmium tetra-oxide (M. Schroder, Chem. Rev. vol. 80, p. 187, 1980) and potassium permanganate (Sheldon and Kochi, in Metal-Catalyzed Oxidation of Organic Compounds, pp. 162-171 and 294-296, Academic Press, New York, 1981).

Regarding the step of epoxide ring opening to the corresponding dihydroxy-ester, this step is usually an acid-catalyzed hydrolysis. Exemplary acid catalysts include, but are not limited to, mineral-based Brönsted acids (e.g., HCl, H2SO4, H3PO4, perhalogenates, etc.), Lewis acids (e.g., TiCl4 and AlCl3), solid acids such as acidic aluminas and silicas or their mixtures, and the like. See, e.g., Chem. Rev. vol. 59, p. 737, 1959; and Angew. Chem. Int. Ed., vol. 31, p. 1179, 1992. The epoxide ring opening to the diol can also be accomplished by base-catalyzed hydrolysis using aqueous solutions of KOH or NaOH.

Regarding the step of esterifying the dihydroxy-ester to form a triester, an acid is typically used to catalyze the reaction between the —OH groups of the diol and the carboxylic acid(s). Suitable acids include, but are not limited to, sulfuric acid (Munch-Peterson, Org. Synth., V, p. 762, 1973), sulfonic acid (Allen and Sprangler, Org Synth., III, p. 203, 1955), hydrochloric acid (Eliel et al., Org Synth., IV, p. 169, 1963), and phosphoric acid (among others). In some embodiments, the carboxylic acid used in this step is first converted to an acyl chloride (or another acyl halide) via, e.g., thionyl chloride or PCl3. Alternatively, an acyl chloride (or other acyl halide) could be employed directly. Where an acyl chloride is used, an acid catalyst is not needed and a base such as pyridine, 4-dimethylaminopyridine (DMAP) or triethylamine (TEA) is typically added to react with an HCl produced. When pyridine or DMAP is used, it is believed that these amines also act as a catalyst by forming a more reactive acylating intermediate. See, e.g., Fersh et al., J. Am. Chem. Soc., vol. 92, pp. 5432-5442, 1970; and Hofle et al., Angew. Chem. Int. Ed. Engl., vol. 17, p. 569, 1978. Additionally or alternatively, the carboxylic acid could be converted into an acyl anhydride and/or such species could be employed directly.

Regardless of the source of the mono-unsaturated fatty acid, in some embodiments, the carboxylic acids (or their acyl derivatives) used in the above-described methods may be derived from biomass. In some such embodiments, this involves the extraction of some oil (e.g., triglyceride) component from the biomass and hydrolysis of the triglycerides of which the oil component is comprised so as to form free carboxylic acids.

In some particular embodiments, wherein the above-described method uses oleic acid for the mono-unsaturated fatty acid, the resulting triester is of the type:

wherein R₂, R₃ and R₄ are independently selected from C₂ to C₂₀ hydrocarbon groups, for instance selected from C₄ to C₁₂ hydrocarbon groups.

Using a synthetic strategy in accordance with that outlined above, oleic acid can be converted to triester derivatives (9,10-bis-hexanoyloxy-octadecanoic acid hexyl ester) and (9,10-bis-decanoyloxy-octadecanoic acid decyl ester). Oleic acid is first esterified to yield a mono-unsaturated ester. The mono-unsaturated ester is subjected to an epoxidation agent to give an epoxy-ester species, which undergoes ring-opening to yield a dihydroxy ester, which can then be reacted with an acyl chloride to yield a triester product.

The strategy of the above-described synthesis utilizes the double bond functionality in oleic acid by converting it to the diol via double bond epoxidation followed by epoxide ring opening. Accordingly, the synthesis begins by converting oleic acid to the appropriate alkyl oleate followed by epoxidation and epoxide ring opening to the corresponding diol derivative (dihydroxy ester).

Variations (i.e., alternate embodiments) on the above-described processes include, but are not limited to, utilizing mixtures of isomeric olefins and or mixtures of olefins having a different number of carbons. This may lead to diester mixtures and triester mixtures in an ester component.

Variations on the above-described processes include, but are not limited to, using carboxylic acids derived from FT alcohols by oxidation.

In some embodiments, a base stock comprises a mixture of one or more PAOs and one or more esters.

In some embodiments, an ashless lubricant composition for use in an internal combustion engine may comprise one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amine antioxidants, diphenylamine antioxidants, polymerized diphenylamine antioxidants, phenolic antioxidants, and combinations thereof.

A suitable exemplary alkylated phenyl-naphthyl amine antioxidant may comprise N-α-naphthyl-N-phenylamine antioxidants (PANA) of formula

Wherein R is H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl, —C(O)C₁-C₁₈ alkyl or —C(O)aryl and R₁, R₂, R₃ and R₄ are each independently H, C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, C₁-C₁₈ alkylamino, C₁-C₁₈ dialkylamino, C₁-C₁₈ alkylthio, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl or C₇-C₂₁ aralkyl.

In some embodiments, PANA antioxidants are of formula

Wherein R₁ and R₂ are each independently H or C₁-C₁₈ alkyl. In certain embodiments R₂ is H and R₁ is a branched chain C₄-C₁₂ alkyl, for example t-butyl, t-octyl or branched nonyl.

Diphenylamine (DPA) antioxidants may be of formula

Wherein R is H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₂-C₁ alkynyl, —C(O)C₁-C₁₈ alkyl or —C(O)aryl and R₁, R₂, R₃ and R₄ are each independently H, C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, C₁-C₁₈ alkylamino, C₁-C₁₈ dialkylamino, C₁-C₁₈ alkylthio, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl or C₇-C₂₁ aralkyl. These may also be polymerized to form oligomers and polymers.

In certain embodiments, diphenylamine antioxidants may be of formula

wherein R₁ and R₂ are each independently H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl or C₇-C₂₁ aralkyl. In certain embodiments, R₁ and R₂ are each independently H, tert-butyl, tert-octyl or branched nonyl.

Alkyl groups are straight or branched chain and include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, tert-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl. Alkyl groups mentioned herein are linear or branched.

The alkyl portion of alkoxy, alkylamine, dialkylamino and alkylthio groups are linear or branched and include the alkyl groups mentioned above.

Alkenyl is an unsaturated alkyl, for instance allyl. Alkynyl includes a triple bond.

Aralkyl includes benzyl, α-methylbenzyl, α,α-dimethylbenzyl, 2-phenylethyl and 2-phenyl-2-propyl.

Cycloalkyl includes cyclopentyl, cyclohexyl and cycloheptyl.

In some embodiments, an ashless lubricant composition for use in internal combustion engine, as described herein, may comprise one or more sulfur-containing additives that may act as secondary antioxidants. Suitable sulfur-containing additives, according to embodiments, may be sulfur containing additives that comprise up to 7 carbon atoms. In one embodiment, the sulfur-containing additive may be a sulfurized isobutylene (e.g., CAS #68425-15-0, CAS #68937-96-2, CAS #68511-50-2). The sulfur-containing additive may be comprise a mixture of sulfur compounds, e.g., with a varying number of sulfur atoms.

For instance, the mixture of sulfur compounds may comprise sulfurized isobutylene with one sulfur atom, sulfurized isobutylene with two sulfur atoms, sulfurized isobutylene with three sulfur atoms, sulfurized isobutylene with four sulfur atoms, sulfurized isobutylene with five sulfur atoms, and mixtures thereof.

In some embodiments, the mixture of sulfur compounds may comprise: 1) from about 2.5% to about 12.5%, from about 5% to about 10%, or from about 7% to about 8% sulfurized isobutylene with one sulfur atom; 2) from about 32.5% to about 42.5%, from about 35% to about 40%, or from about 37% to about 38% sulfurized isobutylene with two sulfur atoms; 3) from about 30% to about 40%, from about 32.5% to about 37.5%, or from about 34% to about 36% sulfurized isobutylene with three sulfur atoms; 4) from about 5% to about 15%, from about 7.5% to about 12.5%, or from about 9% to about 11% sulfurized isobutylene with four sulfur atoms; 5) from about 1% to about 11%, from about 4% to about 9%, or from about 6% to about 7% of sulfurized isobutylene with five carbon atoms; or any mixture thereof of any one of 1) through 5).

In some embodiments, the lubricant composition may further comprise at least one additional sulfur-containing lubricant additives including sulfur-containing hindered phenolic compounds (e.g., CAS #41484-35-9), sulfur-containing rust inhibitors, sulfur-containing friction modifiers and sulfur-containing antiwear additives.

Sulfur-containing hindered phenolic compounds include alkylthiomethylphenols, for example 2,4-di-octylthiomethyl-6-tert-butylphenol, 2,4-di-octylthiomethyl-6-methylphenol, 2,4-di-octylthiomethyl-6-ethylphenol or 2,6-di-dodecylthiomethyl-4-nonylphenol; hydroxylated thiodiphenyl ethers, for example 2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis-(6-tert-butyl-2-methylphenol), 4,4′-thiobis(3,6-di-sec-amylphenol) or 4,4′-bis(2,6-dimethyl-4-hydroxyphenyl) disulfide; S-benzyl compounds, for example octadecyl 4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl 4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide or isooctyl 3,5-di-tert-butyl-4-hydroxy-benzylmercaptoacetate; and esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid, β-(3,5-dicyclohexyl-4-hydroxyphenyl)-propionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid or β-(5-tert-butyl-4-hydroxyphenyl)-3-thiabutyric acid with sulfur-containing mono- or polyhydric alcohols such as thiodiethylene glycol, 3-thiaundecanol or thiapentadecanol.

Sulfur-containing rust inhibitors include, for example, barium dinonylnaphthalene-sulfonates, calcium petroleumsulfonates, alkylthio-substituted aliphatic carboxylic acids, esters of aliphatic 2-sulfocarboxylic acids and salts thereof.

Sulfur-containing friction modifiers may for example be selected from organomolybdenum dithiocarbamates, organomolybdenum dithiophosphates and organomolybdenum compounds based on dispersants and molybdenum disulfide.

Sulfur-containing antiwear additives include sulfurized olefins and vegetable oils, dialkyldithiophosphate esters, zinc dialkyldithiophosphates, alkyl and aryl di- and trisulfides, derivatives of 2,5-dimercapto-1,3,4-thiadiazole, ethyl(bisisopropyloxyphosphinothioyl)-thiopropionate, triphenyl thiophosphate (triphenyl phosphorothioate), tris(alkylphenyl) phosphorothioates and mixtures thereof (for example tris(isononylphenyl) phosphorothioate), diphenylmonononylphenyl phosphorothioate, isobutylphenyl diphenyl phosphorothioate, the dodecylamine salt of 3-hydroxy-1,3-thiaphosphetan 3-oxide, trithiophosphoric acid 5,5,5-tris-isooctyl 2-acetate, derivatives of 2-mercaptobenzothiazole, such as 1-N,N-bis(2-ethylhexyl)aminomethyl-2-mercapto-1H-1,3-benzothiazole, and ethoxycarbonyl 5-octyldithiocarbamate; and dihydrocarbyl dithiophosphate metal salts where the metal may be aluminum, lead, tin manganese, cobalt, nickel, zinc or copper.

A zinc dialkyldithiophosphate salt may be represented as

where R and R′ are independently C₁-C₂₀ alkyl, C₃-C₂₀ alkenyl, C₅-C₁₂ cycloalkyl, C₇-C₁₃ aralkyl or C₆-C₁₀ aryl, for example R and R′ are independently C₁-C₁₂ alkyl.

In some embodiments, the lubricants may be substantially free or free of zinc dialkyldithiophosphates. The term “substantially free” may mean “not intentionally added”, for example may mean ≤1000 ppm (0.1 wt %), ≤750 ppm (0.075 wt %), ≤500 ppm (0.05 wt %), ≤250 ppm (0.025 wt %), ≤100 ppm (0.01 wt %), ≤75 ppm (0.0075 wt %), ≤50 ppm (0.005 wt %), ≤25 ppm (0.0025 wt %), ≤10 ppm (0.001 wt %), ≤5 ppm (0.0005 wt %), ≤2 ppm (0.0002 wt %) or ≤1 ppm (0.0001 wt %) of a zinc dialkyldithiophosphate (or other referenced component) may be present, by weight, based on the weight of the total composition.

In some embodiments, the zinc dialkyldithiophosphate salts in the lubricant composition described herein may deliver less than about 500 ppm phosphorus, less than about 450 ppm phosphorus, less than about 400 ppm phosphorus, less than about 350 ppm phosphorus, less than about 300 ppm phosphorus, less than about 250 ppm phosphorus, less than about 200 ppm phosphorus, less than about 150 ppm phosphorus, less than about 100 ppm phosphorus, or less than about 50 ppm phosphorus, based on the total weight of the lubricant composition.

A suitable dialkyldithiophosphate ester for the lubricant compositions described herein may be represented as

in which R₅ and R₆ independently of one another are C₃-C₁₈ alkyl, C₅-C₁₂ cycloalkyl, C₅-C₆ cycloalkylmethyl, C₉-C₁₀ bicycloalkylmethyl, C₉-C₁₀ tricycloalkylmethyl, phenyl or C₇-C₂₄ alkylphenyl or together are (CH₃)₂C(CH₂)₂ and R₇ and R₈ are independently hydrogen or C₁-C₁₈ alkyl. For example, a dialkyl dithiophosphate ester, CAS #268567-32-4.

In some embodiments, sulfur-containing additives include sulfurized olefins. Suitable olefins include isobutylene, other butylenes, pentenes, propene, mixtures thereof and oligomers thereof. In a certain embodiment, the sulfur-containing additives include sulfurized isobutylene. Sulfurized olefins are described in, for example, U.S. Pat. Nos. 3,471,404, 3,697,499, 3,703,504, 4,194,980, 4,344,854, 5,135,670, 5,338,468 and 5,849,677. Sulfurized olefins include sulfur-containing polyolefins, for example sulfur-containing polyisobutylene compounds, for example, as described in U.S. Pat. No. 6,410,491 and US2005/0153850. In general, sulfurized olefins may be prepared by treating an olefin or an olefinic oligomer or polymer, such as isobutylene or polyisobutylene, with a source of sulfur such as elemental sulfur, hydrogen sulfide or sulfuric acid. Sulfurized olefins include sulfurized polyolefins, for example sulfurized isobutylene includes sulfurized polyisobutylene.

In certain embodiments, sulfur-containing additives may include one or more di-tert-alkyl polysulfides such as di-tert-butyl polysulfide (CAS #68937-96-2), di-tert-dodecyl polysulfide (CAS #68425-15-0) or di-tert-nonyl polysulfide.

The one or more antioxidants, together in total, may be present from any of about 0.20 wt % (weight percent), about 0.25 wt %, about 0.30 wt %, about 0.35 wt %, about 0.40 wt %, about 0.45 wt %, about 0.50 wt %, about 0.55 wt %, about 0.60 wt %, about 0.65 wt %, about 0.70 wt %, about 0.75 wt %, about 0.80 wt %, about 0.85 wt %, about 0.90 wt %, about 0.95 wt %, about 1.0 wt %, about 1.25 wt %, about 1.50 wt %, about 1.75 wt %, about 2.0 wt %, about 2.25 wt %, about 2.50 wt %, about 2.75 wt %, about 3.0 wt %, about 3.25 wt %, about 3.50 wt %, about 3.75 wt %, about 4.0 wt %, about 4.25 wt %, about 4.50 wt %, about 4.75 wt %, or about 6.0 wt %, up to any of about 6.25 wt %, about 6.50 wt %, about 6.75 wt %, about 7.0 wt %, about 7.25 wt %, about 7.50 wt %, about 7.75 wt %, about 8.0 wt %, about 8.25 wt %, about 8.50 wt %, about 8.75 wt %, about 9.0 wt %, about 9.25 wt %, about 9.50 wt %, about 9.75 wt %, or about 10.0 wt %, based on the total weight of the formulated lubricant composition.

The one or more N-α-naphthyl-N-phenylamine antioxidants and the one or more diphenylamine antioxidants may be present in a weight/weight ratio of from any of about 1/9, about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2 or about 1/1 to any of about 2/1, about 3/1, about 4/1, about 5/1, about 6/1, about 7/1, about 8/1 or about 9/1. In certain embodiments, the weight/weight ratio of the one or more N-α-naphthyl-N-phenylamine antioxidants to the one or more diphenylamine antioxidants may be from any of about 1/1, about 1/2, about 1/3 or about 1/4 to any of about 1/5, about 1/6, about 1/7, about 1/8 or about 1/9. In other embodiments, the weight/weight ratio of the one or more N-α-naphthyl-N-phenylamine antioxidants to the one or more diphenylamine antioxidants may be from about 1/1 or about 1/2 to about 1/3.

The sulfur provided by the one or more sulfur-containing additives may be present, in total, from any of about 50 ppm (parts per million), about 75 ppm, about 100 ppm, about 125 ppm, about 150 ppm, about 175 ppm about 200 ppm, about 225 ppm, about 250 ppm, about 275 ppm, about 300 ppm, about 325 ppm, about 350 ppm, about 375 ppm, about 400 ppm or about 425 ppm to any of about 450 ppm, about 475 ppm, about 500 ppm, about 525 ppm, about 550 ppm, about 575 ppm, about 600 ppm, about 625 ppm, about 650 ppm, about 675 ppm, about 700 ppm, about 725 ppm, about 750 ppm, about 775 ppm, about 800 ppm, about 825 ppm, about 850 ppm, about 875 ppm, about 900 ppm, about 925 ppm, about 950 ppm, about 975 ppm or, about 1000 ppm, by weight, based on the total weight of the lubricant composition.

The lubricant compositions may further comprise one or more non-sulfur-containing lubricant additives selected from the group consisting of further antioxidants, antiwear agents (e.g., ashless antiwear agents), dispersants, pour point depressants, detergents, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, viscosity index improvers, viscosity modifiers, fluid-loss additives, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, anti-foam agents, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants and others.

In certain embodiments, lubricant compositions for use in an internal combustion engine as described herein may comprise one or more of an ashless antiwear component, dispersants, pour point depressants, friction modifiers, and metal deactivators.

A suitable ashless antiwear component for an internal combustion engine lubricant composition may comprise a phosphorus derivative. The ashless antiwear component may be present in the internal combustion engine lubricant composition in an amount ranging from about 0.5 wt %, about 0.75 wt %, about 1.0 wt %, about 1.25 wt %, about 1.50 wt %, about 1.75 wt %, about 2.0 wt %, about 2.25 wt %, about 2.50 wt %, about 2.75 wt %, about 3.0 wt %, about 3.25 wt %, about 3.50 wt %, about 3.75 wt %, about 4.0 wt %, about 4.25 wt %, about 4.50 wt %, about 4.75 wt %, about 5.0 wt %, about 5.25 wt %, about 5.5 wt %, about 5.75 wt %, or about 6.0 wt %, up to any of about 6.25 wt %, about 6.50 wt %, about 6.75 wt %, about 7.0 wt %, about 7.25 wt %, about 7.50 wt %, about 7.75 wt %, about 8.0 wt %, about 8.25 wt %, about 8.50 wt %, about 8.75 wt %, about 9.0 wt %, about 9.25 wt %, about 9.50 wt %, about 9.75 wt %, or about 10.0 wt %, based on the total weight of the formulated lubricant composition.

A suitable dispersant for an internal combustion engine lubricant composition may be present in the lubricant composition in an amount ranging from about 0.5 wt %, about 0.75 wt %, about 1.0 wt %, about 1.25 wt %, about 1.50 wt %, about 1.75 wt %, about 2.0 wt %, about 2.25 wt %, about 2.50 wt % up to any of about 2.75 wt %, about 3.0 wt %, about 3.25 wt %, about 3.50 wt %, about 3.75 wt %, about 4.0 wt %, about 4.25 wt %, about 4.50 wt %, about 4.75 wt %, or about 5.0 wt %.

A suitable pour point depressant for an internal combustion engine lubricant composition may be present in the lubricant composition in an amount ranging from about 0.05 wt %, about 0.075 wt %, about 0.10 wt % up to any of about 0.125 wt %, about 0.150 wt %, about 0.175 wt %, or about 0.20 wt %.

A suitable friction modifier for an internal combustion engine lubricant composition may be present in the lubricant composition in an amount ranging from about 0.2 wt %, about 0.3 wt %, about 0.4 wt %, about 0.5 wt % up to any of about 0.6 wt %, about 0.7 wt %, about 0.8 wt %, or about 0.9 wt %.

A suitable metal deactivator for an internal combustion engine lubricant composition may be present in the lubricant composition in an amount ranging from about 0.1 wt %, about 0.2 wt %, about 0.3 wt %, about 0.4 wt %, about 0.5 wt % up to any of about 0.6 wt %, about 0.7 wt %, about 0.8 wt %, or about 0.9 wt %.

In certain embodiments, disclosed is a process comprising running an internal combustion engine with an ashless lubricant composition. The ashless lubricant composition may be any one of the lubricant compositions described herein. For instance, in certain embodiments, the lubricant composition may comprise any of the base oils described herein, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amines antioxidants antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives.

In certain embodiments, disclosed is a system comprising an internal combustion engine and an ashless lubricant composition. The ashless lubricant composition may be any one of the lubricant compositions described herein. For instance, in certain embodiments, the lubricant composition may comprise any of the base oils described herein, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amines antioxidants antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives.

The term “base oil” is synonymous with “base stock”, “lubricating base oil” or “lubricating base stock”.

The term “fully formulated lubricating oil” means a finished lubricating oil for use containing a base stock and an additive package and is synonymous with “formulated oil” or “finished oil”.

“Centistoke,” abbreviated “cSt,” is a unit for kinematic viscosity of a fluid (e.g., a lubricant), wherein 1 centistoke equals 1 millimeter squared per second (1 cSt=1 mm²/s).

The lubricant compositions in some embodiments have a kinematic viscosity at 100° C. of from any one of about 2 cSt, about 3 cSt, about 4 cSt, about 5 cSt, about 6 cSt or about 7 cSt to any one of about 8 cSt, about 9 cSt, about 10 cSt, about 11 cSt, about 12 cSt, about 13 cSt, about 14 cSt, about 15 cSt, about 16 cSt, about 17 cSt, about 18 cSt, about 19 cSt or about 20 cSt.

U.S. patents, U.S. patent applications and published U.S. patent applications discussed herein are hereby incorporated by reference.

Unless otherwise indicated, all parts and percentages are by weight. Weight percent (wt %), if not otherwise indicated, is based on an entire composition free of any volatiles.

For simplicity of explanation, the embodiments of the methods of this disclosure are depicted and described as a series of acts. However, acts in accordance with this disclosure can occur in various orders and/or concurrently, and with other acts not presented and described herein. Furthermore, not all illustrated acts may be required to implement the methods in accordance with the disclosed subject matter. In addition, those skilled in the art will understand and appreciate that the methods could alternatively be represented as a series of interrelated states via a state diagram or events.

In the foregoing description, numerous specific details are set forth, such as specific materials, dimensions, processes parameters, etc., to provide a thorough understanding of the present invention. The particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. Reference throughout this specification to “an embodiment”, “certain embodiments”, or “one embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “an embodiment”, “certain embodiments”, or “one embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

The present invention has been described with reference to specific exemplary embodiments thereof. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. Various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art and are intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A process for lubricating an internal combustion engine, the process comprising adding a lubricant composition to an internal combustion engine, wherein the lubricant composition comprises: a base oil, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amines antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives.
 2. The process of claim 1, wherein the one or more antioxidants, in total, are present from about 0.2 wt % to about 10.0 wt %, based on the total weight of the lubricant composition.
 3. The process of any one of the preceding claims, wherein a sulfur concentration provided by the one or more sulfur-containing additives, in total, ranges from about 75 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.
 4. The process of any one of the preceding claims, wherein the one or more antioxidants comprises N-α-naphthyl-N-phenylamine antioxidants of formula

wherein R is H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl, —C(O)C₁-C₁₈ alkyl or —C(O)aryl and R₁, R₂, R₃ and R₄ are each independently H, C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, C₁-C₁₈ alkylamino, C₁-C₁₈ dialkylamino, C₁-C₁₈ alkylthio, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl or C₇-C₂₁ aralkyl.
 5. The process of any one of the preceding claims, wherein the one or more antioxidants comprises diphenylamine antioxidants of formula

wherein R is H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl, —C(O)C₁-C₁₈ alkyl or —C(O)aryl and R₁, R₂, R₃ and R₄ are each independently H, C₁-C₁₈ alkyl, C₁-C₁₈ alkoxy, C₁-C₁₈ alkylamino, C₁-C₁₈ dialkylamino, C₁-C₁₈ alkylthio, C₂-C₁₈ alkenyl, C₂-C₁₈ alkynyl or C₇-C₂₁ aralkyl.
 6. The process of claim 4, wherein the N-α-naphthyl-N-phenylamine antioxidants are of formula

wherein R₁ and R₂ are each independently H or C₁-C₁₈ alkyl.
 7. The process of claim 6, wherein R₂ is H and R₁ is t-butyl, t-octyl or branched nonyl.
 8. The process of claim 5, wherein the diphenylamine antioxidants are of formula

wherein R₁ and R₂ are each independently H, C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl or C₇-C₂₁ aralkyl.
 9. The process of claim 8, wherein R₁ and R₂ are each independently H, tert-butyl, tert-octyl or branched nonyl.
 10. The process of any one of the preceding claims, wherein the lubricant composition comprises sulfur-containing additives selected from a group consisting of sulfur-containing hindered phenolic compounds, sulfur-containing rust inhibitors, sulfur-containing friction modifiers and sulfur-containing antiwear additives.
 11. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more sulfur-containing additives selected from a group consisting of 2,4-di-octylthiomethyl-6-tert-butylphenol, 2,4-di-octylthiomethyl-6-methylphenol, 2,4-di-octylthiomethyl-6-ethylphenol or 2,6-di-dodecylthiomethyl-4-nonylphenol, 2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis-(6-tert-butyl-2-methylphenol), 4,4′-thiobis(3,6-di-sec-amylphenol), 4,4′-bis(2,6-dimethyl-4-hydroxyphenyl) disulfide, octadecyl 4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl 4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxy-benzylmercaptoacetate and esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid, β-(3,5-dicyclohexyl-4-hydroxyphenyl)-propionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid or β-(5-tert-butyl-4-hydroxyphenyl)-3-thiabutyric acid with thiodiethylene glycol, 3-thiaundecanol or thiapentadecanol.
 12. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more sulfur-containing additives selected from a group consisting of organomolybdenum dithiocarbamates, organomolybdenum dithiophosphates and organomolybdenum compounds based on dispersants and molybdenum disulfide.
 13. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more sulfur-containing additives selected from a group consisting of sulfurized olefins, sulfurized vegetable oils, dialkyldithiophosphate esters, zinc dialkyldithiophosphates, alkyl or aryl di- or tri-sulfides, derivatives of 2,5-dimercapto-1,3,4-thiadiazole, ethyl(bisisopropyloxyphosphinothioyl)-thiopropionate, triphenyl thiophosphate, tris(alkylphenyl) phosphorothioates, diphenylmonononylphenyl phosphorothioate, isobutylphenyl diphenyl phosphorothioate, a dodecylamine salt of 3-hydroxy-1,3-thiaphosphetan 3-oxide, trithiophosphoric acid 5,5,5-tris-isooctyl 2-acetate, derivatives of 2-mercaptobenzothiazole, ethoxycarbonyl 5-octyldithiocarbamate and dihydrocarbyl dithiophosphate metal salts.
 14. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more sulfur-containing additives selected from a group consisting of sulfurized olefins.
 15. The process of claim 14, wherein the sulfurized olefins comprise sulfurized isobutylene.
 16. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more sulfur-containing additives selected from a group consisting of di-tert-alkyl polysulfides.
 17. The process of claim 16, wherein the di-tert-alkyl polysulfides are selected from a group consisting of di-tert-butyl polysulfide, di-tert-dodecyl polysulfide and di-tert-nonyl polysulfide.
 18. The process of any one of the preceding claims, wherein the lubricant composition comprises a base oil selected from a group consisting of Group II, Group III and Group IV base oils.
 19. The process of any one of the preceding claims, wherein the lubricant composition comprises a base oil selected from a group consisting of polyalphaolefins.
 20. The process of any one of the preceding claims, wherein the lubricant composition comprises a base oil selected from a group consisting of synthetic esters.
 21. The process of any one of the preceding claims, wherein the lubricant composition comprises a base oil that comprises one or more polyalkylene glycols.
 22. The process of any one of the preceding claims, wherein the lubricant composition comprises one or more N-α-naphthyl-N-phenylamine antioxidants and one or more diphenylamine antioxidants and wherein a weight/weight ratio of N-α-naphthyl-N-phenylamine antioxidants to diphenylamine antioxidants is from about 1/9 to about 9/1.
 23. The process of any one of the preceding claims, wherein the lubricant composition comprises a base oil is an amount of from about 80 wt % to about 99.7 wt %, based on the total weight of the lubricant composition.
 24. The process of any one of the preceding claims, wherein the lubricant composition comprises less than 0.1 wt % of zinc dialkyldithiophosphate salts, based on the total weight of the lubricant composition.
 25. The process of claim 24, wherein the lubricant composition is substantially free of zinc dialkyldithiophosphate salts.
 26. The process of any one of claims 24-25, wherein the zinc dialkyldithiophosphate salts delivers less than about 500 ppm phosphorus by weight, based on the total weight of the lubricant composition.
 27. The process of claim 26, wherein the zinc dialkyldithiophosphate salts delivers less than about 300 ppm phosphorus by weight, based on the total weight of the lubricant composition.
 28. The process according to any one of the preceding claims, wherein a sulfur concentration provided by the one or more sulfur-containing additives, in total, ranges from about 50 ppm to about 1000 ppm by weight, based on the total weight of the lubricant composition.
 29. The process according to any one of the preceding claims, wherein the lubricant composition comprises less than about 0.1 wt % overbased calcium, magnesium, salts of alkyl aromatic sulfonates, phenates, or salicylates, independently or in total, based on the total weight of the lubricant composition.
 30. The process according to any one of the preceding claims, wherein the lubricant composition further comprises an ashless antiwear components, dispersants, pour point depressants, friction modifiers, and metal deactivators.
 31. The process of claim 30, wherein the ashless antiwear components comprise a phosphorus derivative.
 32. The process of any one of claims 30-31, wherein the ashless antiwear components are present from about 0.5 wt % to about 10.0 wt %, based on the total weight of the lubricant composition.
 33. The process of any one of claims 30-32, wherein the dispersants are present from about 0.5 wt % to about 5.0 wt %, based on the total weight of the lubricant composition.
 34. The process of any one of claims 30-33, wherein the pour point depressants are present from about 0.05 wt % to about 0.2 wt %, based on the total weight of the lubricant composition.
 35. The process of any one of claims 30-34, wherein the friction modifiers are present from about 0.2 wt % to about 0.9 wt %, based on the total weight of the lubricant composition.
 36. The process of any one of claims 30-35, wherein the metal deactivators are present from about 0.1 wt % to about 0.9 wt %, based on the total weight of the lubricant composition.
 37. A system comprising an internal combustion engine and an ashless lubricant composition, wherein the ashless lubricant composition comprises: a base oil, one or more antioxidants selected from the group consisting of alkylated phenyl-naphthyl amines antioxidants, diphenylamine antioxidants, phenolic antioxidants, and combinations thereof, and one or more sulfur-containing additives. 